4DIX

Crystal structure of the Ig-PH domain of actin-binding protein SCAB1

Summary for 4DIX

• Entry DOI: 10.2210/pdb4dix/pdb
• Related: 4DJG
• Descriptor: Plectin-related protein, MALONATE ION (3 entities in total)
• Functional Keywords: ph domain, ig domain, malonate ion, beta sheet, ph superfold, cytosolic, protein binding
• Biological source: Arabidopsis thaliana (mouse-ear cress,thale-cress)
• Total number of polymer chains: 2
• Total formula weight: 49952.22

Authors

Zhang, W.,Ye, K. (deposition date: 2012-02-01, release date: 2012-02-29, Last modification date: 2024-03-20)

Primary citation

Zhang, W.,Zhao, Y.,Guo, Y.,Ye, K.
Plant actin-binding protein SCAB1 is dimeric actin cross-linker with atypical pleckstrin homology domain
J.Biol.Chem., 287:11981-11990, 2012

PubMed Abstract: SCAB1 is a novel plant-specific actin-binding protein that binds, bundles, and stabilizes actin filaments and regulates stomatal movement. Here, we dissected the structure and function of SCAB1 by structural and biochemical approaches. We show that SCAB1 is composed of an actin-binding domain, two coiled-coil (CC) domains, and a fused immunoglobulin and pleckstrin homology (Ig-PH) domain. We determined crystal structures for the CC1 and Ig-PH domains at 1.9 and 1.7 Å resolution, respectively. The CC1 domain adopts an antiparallel helical hairpin that further dimerizes into a four-helix bundle. The CC2 domain also mediates dimerization. At least one of the coiled coils is required for actin binding, indicating that SCAB1 is a bivalent actin cross-linker. The key residues required for actin binding were identified. The PH domain lacks a canonical basic phosphoinositide-binding pocket but can bind weakly to inositol phosphates via a basic surface patch, implying the involvement of inositol signaling in SCAB1 regulation. Our results provide novel insights into the functional organization of SCAB1.

PubMed: 22356912
DOI: 10.1074/jbc.M111.338525

Experimental method

X-RAY DIFFRACTION (1.7 Å)